Variable impact drill



`Fin. 24, A1961 C, FULOP VARIABLE IMPACT DRILL 3 Sheets-Sheet 1 FiledDeo. 8, 1959 INVENTOR. C HAR/ E5 Fu/ op ATTORNEY Jan. 24, 1961 FiledDec. 8, 1959 C. FULOP VARIABLE IMPACT DRILL 3 Sheets-Sheet 2 INVENTOR.CHA LESQyF/ULOP N92/22] Jan. 24, 1961 c. FuLoP VARIABLE IMPACT DRILL 5Sheets-Sheet 3 Filed Dec. 8, 1959 INVENTOR CHA/@L55 FULOP BY @MQW/WATTO/w57( rates Filed Dec. 8, 1959, Ser. No. 858,121

2 Claims. (Cl. 7422) This invention relates to vibrating drills andparticularly to such a tool whose impact can be adjusted between widelimits.

The primary object of this invention is to provide an electric drillthat is a combination continuous or impact drill.

Another object is to provide an electric or motor driven drill of thetype stated that can be progressively adjusted to operate between stagesof maximum impact and no impact at all.

Another object is to provide a device of the type stated whose impactforce can be changed while the drill is in operation, if it is sodesired.

A further object is to provide such a device whose impact force can bevaried between zero and the maximum, by rotating its control member lessthan one-half a turn.

Another object is to provide a device that is rugged in structure,reliable in operation and relatively inexpensive to manufacture.

These and other objects of the invention will become apparent from areading of the following specication and claims, together with theaccompanying drawing, wherein:

Figure l is a side elevation of the variable impact vibrating drill thatis the subject of this invention;

Figure 2 is a longitudinal sectional view of the same, showing theimpact hammer at the end of its maximum stroke;

Figure 3 is a front end view of the device with the drill chuck removed;

Figure 4 is a longitudinal sectional view showing the impact hammerpositioned at its maximum position just prior to delivering its maximumimpact stroke:

Figure 5 is a longitudinal sectional view showing the impact hammer inits inoperative position, with the device acting as a continuous drill;

Figure 6 is an exploded View of the device;

Figure 7 is a perspective view of the spindle housing with its capremoved;

Figure 8 is a perspective view of the hammer; and

Figure 9 is a perspective view of the anvil with the cam pins removed.

Referring more particularly to the drawings, there is seen in Figure lthe variable impact vibrating drill-that is the subject of thisinvention, broadly indicated by reference numeral 10.

Conducive to a better understanding of the invention, it may be well topoint out that the drilling of holes in stone, concrete cinder-block andsimilar granular materials requires that the drill bit be given ahammering or impact action, as well as a rotary one.

Again, different materials and different size bits require varieddegrees of impact for the most efficient operation of the drill.

In the instant device the impact is created by moving a hammer element40 sharply against an anvil member 35 mounted on a rotating spindle 20,at the end of which the drill bit holding chuck 50 is mounted. Themanner Patented Jan. 24, 152361 of varying the force of the hammer blowsbetween zero and the maximum and the mechanical structure employed toeiect the desired result will be explained hereinafter.

Again referring to the drawings, reference numeral 11 indicates the caseof portable electric motor of the type capable of being held in thehands in the manner of a conventional electric drill and has the usualhard grip 52, as seen in Figure 3, and motor shaft 12 extending beyondthe case, surrounded by a clamp element 16 having a draw bolt 51, as ismost clearly seen in Figures 1. 2 and 3.

Reference numeral 13 indicates a spindle housing mounted on the motorcase 11, at its base end 15 within the clamp 16, co-axially with the endof the motor shaft 12.

A spindle 20 is threadedly mounted at 21 on the end of the motor shaft12, forming a continuation thereof, extending through the housing 13.

A disc-shaped anvil 35 having a threaded bore 36 is rigidly mounted onthe spindle 20 at threaded section 22. The anvil has four equi-spacedbores 37 therethrough, extending parallel to the spindle 20, as is mostclearly seen in Figure 9. Four plungers 31, 32, 33 and 34 are slidablymounted in the anvil holes 37.

Each plunger has a at base end and .a semi-spherical head end. Theover-all length of each plunger is such that when its flat end is ilushwith the anvil face 3S, its

semi-spherical end will protrude beyond the anvil impact face 39 to theextent that its equator will lie in the plane of anvil impact face 39,as seen most clearly in Figure 2.

Reference numeral 40 indicates a cylindrical hammer having a centralbore 41 through which the unthreaded portion 24 of the spindle 20passes. The hammer 40 is free to slide lengthwise of the spindle 20.

Referring to Figure 9, it is seen that hammer 40 has four inclined camsurfaces 42 terminating in 4 dat striking surfaces 43. A longitudinalslot 45 is cut in the edge of the hammer 40. This slot 45 is engaged bya pin or ball 27 mounted on the inner face of the spindle housing 13.When the hammer is so engaged it is free to move lengthwise of thespindle, but is locked against rotation.

Reference numeral 46 indicates a coil spring that is mounted over thespindle section 24, as seen in Figures 2, 4 and 5. The spring ispositioned between the collar 25 at the base of the spindle 20 and thehammer 40. Two washers 47 and 49 separated by a ball bearing ring 48provides a frictionless bearing surface for one end of the spring 46.The other end of the spring is seated in a socket 44 in the hammer 40.The spring 46 acts to constantly bias the hammer 40 against the anvilirnpact face 39.

Reference numeral 17 indicates a closure cap that telescopically fitsover the spindle housing 13. The cap 17 has an end wall 28 with acentral bore 26 through which the threaded end 23 ofthe spindle extends.The cap 17 is locked to the spindle housing 13 through a peg or ball 18which engages a spiral groove 14 cut in the outer wall of the spindlehousing 13. A bearing ring 26 and a pressure washer 30 are mounted onthe spindle 20 between the end wall 28 of the cap and the face 38 of theanvil 35.

An impact adjusting handle 19 is threadedly mounted through the cap 17.The end of the handle may be screwed into engagement with the spindlehousing 13 to lock the cap in place. By loosening the handle and usingit to rotate the cap 17 on the `housing groove 14 the cap end wall 28can be made to move toward the end face 38 of the anvil as seen inFigures 2 and 4, or away from f the end face 38 as seen in Figure 5.

the maximum impact of which the device is capable the cap 17 is turnedby means of the handle 19 to the position illustrated in Figures 2 and4. By referring to said Figure 2, it will be noted that the pressurewasher 30 is pressed tightly against rthe face 38 of the anvil, therebycausing the plungers 32 and 33 (and plungers 31 and 34, not visible) totake a position wherein their iiat ends are liush with the anvil face 38and their semi-spherical ends protrude beyond the anvil impact face 39to the point wherein their equators lie in the plane of the impact face39.

When the drill motor is started, the spindle 20 and attached anvil 3Swill rotate relative to the hammer 40 which is held `Stationary by thespindle housing ball 27. This in turn causes the ball ends of theplungers 31, 32, 33 and 34 to travel past the cam faces 42 of the hammer40. Since the hammer 40 is locked against rotation by the ball 27,engaged in its slot 45, but is free to travel longitudinally of thespindle surface 24, the moving plungers will ride up the inclined camfaces 42 thereby moving the hammer 40 away from the anvil 35 against thebiasing action of the spring 46. When the plungers have travelled to thetop edge of the inclined cam surfaces 42, as seen in Figure 4, thehammer 40 is under maximum pressure from the spring 46. As the plungersmove past the drop off points 43 of the inclined cam surfaces 42, thehammer 40 is snapped back in contact with the anvil impact face 39 bythe expansion of the spring 46 to the position illustrated in Figure 2,causing the hammer surfaces 43 to strike the anvil a sharp blow. As thespindle 2 0 continues to rotate the plungers 31, 32, 33 and 34repeatedly ride across the cam surfaces 42, and then drop off to permitthe hammer to return to its normal position against the anvil impactface 39, thus creating a uniform hammering action.

It will be evident that the travel distance of the hammer 40 and theresultant compression of the spring 46 can be varied between zero andthe maximum by backing the cap 17 ofi the housing 13 so that its endwall 23 will move away from the anvil face 38, thereby permitting thepressure washer 30 to similarly move to create a space into which theplungers may move beyond the face 33 of the anvil. This in turn reducesthe degree of protrusion of the ball end of the plunger beyond the anvilimpact face 39. As a result the hammer is pushed away a shorterdistance, thereby reducing the force of its return impactproportionately. Thus the force of the impact can be quickly, easily,and accurately adjusted by rotating the cap 17 a delinite amount,usually less than a quarter turn.

If the cap 17 is backed off to the point illustrated in Figure 5, novibration or impact will take place and the drill will act as anordinary continuous drill, since the ball ends of the plungers now lieflush with the anvil surface 39, and the two impact faces 39 and 43 willride smoothly against each other. lt is further evident that the degreeof impact can be continuously varied from zero to the maximum, evenwhile the drill is in operation. Since the device can be made to operateas an ordinary continuous drill, it can be so used, when an impact drillis not needed. Thus a second special drill need not be purchased toprovide these alternate types of drilling action.

It will now be clear that there has been provided a device whichaccomplishes the objectives heretofore set forth.

While the invention has been disclosed in its preferred form, it is tobe understood that the specific embodiment thereof as described andillustrated herein is not to be considered in a limited sense, as theremay be other forms or modifications of the invention which should alsobe construed to come within the scope of the appended claims.

I claim:

l. A variable impact drill, comprising in combination, an electricmotor, including a drive shaft, mounted in a case having a hand grip; aspindle housing mounted on the case at the drive shaft; a spindlemounted on the end of the shaft, forming a continuation thereof, andextending through the housing; tool holding means mounted on the freeend of the spindle; a cylindrical anvil member, including a ilat impactface, mounted on the spindle within the housing and having a pluralityof spaced plungers slidably mounted therethrough and movable between aiirst position, in which they extend beyond the impact face of theanvil, and a second position, wherein they lie flush with said face; ahammer member nonrotatably mounted on the spindle, within the housing,and slidable longitudinally thereof relative to the anvil member; thehammer having a series of inter-connected inclined cam tracks arrangedin circular configuration and engageable by the anvil plungers when theyare in their rst positions; spring means engaged with the hammer memberto normallybias the hammer cam tracks against the impact face of theanvil, and, impact control means for progressively moving the anvilplungers between their rst and second positions.

2.V A variable impact drill, comprising in combination, an electricmotor, including a drive shaft, mounted in a case having a hand grip; aspindle housing mounted on the case at the drive shaft; a spindlemounted on the end of the shaft, forming a continuation thereof, andextending through the housing; a closure cap threadedly mounted on thespindle housing having an end wall with a central bore for passage ofthe spindle therethrough; tool holding means mounted on the free end ofthe spindle; a cylindrical anvil member, including a flat impact face,mounted on the spindle -within the housing, and rotatable therewith, theanvil member having a plurality of equi-spaced bores therethroughparallel to the spindle axis; plungers whose over-all lengths aregreater than the thickness of the anvil, and having base and headends,slidably mounted in each of said anvil bores, the plungers beingmovable between a first position, in which their head endsV will extendbeyond the impactY face of the anvil, and a second position, whereinthey lie iiush with said face; a hammer member non-rotatably mounted onthe spindle within the housing and slidable longitudinally thereofrelative to the anvil member; the hammer having'a series ofinter-connectedV inclined cam tracks arranged in circular configurationand engageable by the anvil plungers when they are in their rstpositions; springmeans engaged with the hammer member to normally biasthe hammer cam tracks against the impact face of the anvil; and apressure washer mounted on the spindle between the end wall of the capand the anvil, and engageable with the base ends of the plungers, thewasher being movable between adjusted positions, longitudinally of thespindle, toward or away from the anvil member, by rotation of the cap,whereby the engaged plungers are moved between their first and secondpositions, respectively.

References Cited in the file of' this patent UNITED STATES PATENTS2,545,934 Bergeson Dec. 19, 1950 2,630,723 Gridley Mar. 10, 19532,775,898 Baier Jan. l, 1957 2,794,621. Beeson June 4, 1957

